A person who is an ass fanatic. Usually grabbing, smacking and engaging in sexual activity with the ass. It could also be known as a person who sticks objects up their ass (Ex: A pen, dildo, a fairly small animal, etc.)

There is also a mythical beast called an Anal Munchkin. It could, and would, sneak up and fuck you in the ass from behind in such a behaviour that the victim would lose consciousness. Then afterwards, it would shrink itself to a very tiny size and climb up inside the victims asshole and then return to normal size, making the person's ass bigger than usual. Then it would live off shit for the rest of it's life without ever leaving the asshole. Though, at rare occasions, it would leave the ass at night for some fresh air when the person is sleeping, then return shortly after that before the person wakes up.